Measure 3 (2015) Management Plan for Antarctic Specially Protected Area No. 103 ARDERY ISLAND AND ODBERT ISLAND, BUDD COAST, WILKES LAND, EAST ANTARCTICA Introduction Ardery Island and Odbert Island (66°22’20”S; 110°29’10”E, Map A) were originally designated as Specially Protected Area No. 3, through Recommendation IV-III (1966), after a proposal by Australia. A management plan for the Area was adopted under Recommendation XVII-2 (1992). In accordance with Decision 1 (2002), the site was redesignated and renumbered as Antarctic Specially Protected Area (ASPA) No. 103. Revised management plans for the ASPA were adopted under Measure 2 (2005) and Measure 3 (2010). The Area is primarily designated to protect the unusual assemblage of breeding colonies of several species of petrel. The Antarctic petrel (Thalassoica antarctica) and the southern fulmar (Fulmarus glacialoides) are of particular scientific interest. 1. Description of values to be protected The Area is designated primarily to protect the assemblage of four fulmarine petrels at Ardery Island and Odbert Island (Map B and C). The four species of fulmarine petrels, all belonging to different genera, are Antarctic petrels, southern fulmars, Cape petrels (Daption capense), and snow petrels (Pagodroma nivea). All breed in the Area in sufficient numbers to allow comparative study. Study of these four genera at one location is of high ecological importance in understanding their responses to changes in the Southern Ocean ecosystem. The Antarctic petrel is the only species in the genus Thalassoica; they occur most commonly in the Ross and Weddell seas and are much less abundant in East Antarctica. Similarly, the southern fulmar inhabits islands mainly near the Antarctic Peninsula and the islands of the Scotia Arc where about a quarter of its global population resides. Since southern fulmars require steeper slopes as breeding habitat (to allow falling away from the colony when becoming airborne) than Antarctic petrels, this species is more prone to suffer reductions in breeding success in poor weather conditions. Both islands are also occupied by breeding populations of Wilson's storm petrels (Oceanites oceanicus) and Antarctic skuas (Catharacta maccormicki). Odbert Island also supports a breeding population of Adélie penguins (Pygoscelis adeliae). 2. Aims and Objectives Management of Ardery Island and Odbert Island aims to: avoid degradation of, or substantial risk to, the values of the Area by preventing unnecessary human disturbance; allow scientific research on the ecosystem and physical environment, particularly on the avifauna, provided it is for compelling reasons which cannot be served elsewhere; minimise the possibility of introduction of pathogens which may cause disease in bird populations within the Area; minimise the possibility of introduction of alien plants, animals and microbes to the Area; allow for the gathering of data on the population status of the bird species on a regular basis; and allow visits for management purposes in support of the aims of the management plan. ATCM XXXVIII Final Report 3. Management activities The following management activities shall be undertaken to protect the values of the Area: a copy of this Management Plan shall be made available at Casey station and to ships visiting the vicinity; the Area shall be visited as necessary, preferably no less than once every five years, to assess whether it continues to serve the purposes for which it was designated, and to ensure that management activities are adequate: and the Management Plan shall be reviewed at least every five years. 4. Period of designation Designation is for an indefinite period. 5. Maps Map A: Antarctic Specially Protected Area No 103, Ardery Island and Odbert Island, Budd Coast, Wilkes Land, East Antarctica. The inset map indicates the location in relation to the Antarctic continent. Map B: Antarctic Specially Protected Area No 103, Ardery Island: Topography and Bird Distribution. Map C: Antarctic Specially Protected Area No 103, Odbert Island: Topography and Bird Distribution. Map D: Antarctic Specially Protected Area No 103: Ardery Island and Odbert Island: Helicopter approach and landing sites. Specifications for all maps: Horizontal Datum: WGS84; Vertical Datum: Mean Sea Level 6. Description of the Area 6(i) Geographical co-ordinates, boundary markers and natural features Ardery Island (66°22’15”S, 110°27’0”E) and Odbert Island (66°22’24”S, 110°32’28”E) are among the southernmost of the Windmill Islands in the south of Vincennes Bay, off the Budd Coast of Wilkes Land, Eastern Antarctica. The Area comprises both islands down to low water mark. Topography Ardery Island and Odbert Island are located 5 km and 0.6 km, respectively, to the west of Robinson Ridge, south of Casey station. Odbert Island is approximately 2.7 km long and 0.8 km wide. It has a rocky coast which rises steeply from the sea to a plateau. The highest point is 90 m altitude. The plateau is dissected by a series of valleys which run to the south from the high flat rim on the northern side. These valleys are snow covered in winter. The hill tops remain essentially ice and snow free. In some years, the island remains joined to Robinson Ridge on the mainland by sea ice. Ardery Island is a steep, ice free island approximately 1.2 km long and 0.8 km wide, with an east-west orientation. The highest point is 117 m above sea level. The terrain on both islands is rugged and dissected by fissures. The cliffs are fractured and have narrow exposed ledges which in summer are occupied by nesting sea birds. On the hillsides and plateau region, the exposed rock is ice-smoothed and the valley floors are covered with moraine. The islands have undergone isostatic rebound. Moraine and solifluction debris is abundant at heights in excess of 30 metres above mean sea level but considerably less at lower altitudes. Geology ASPA No 103 - Ardery Island and Odbert island The Windmill Islands region represents one of the eastern most outcrops of a Mesoproterozoic low-pressure granulite facies terrain that extends west to the Bunger Hills and further to the Archaean complexes in Princess Elizabeth Land, to minor exposures in the east in the Dumont d’Urville area and in Commonwealth Bay. The total outcrop areas do not exceed more than a few square kilometres. The Mesoproterozoic outcrop of the Windmill Islands and the Archaean complexes of Princess Elizabeth Land are two of the few major areas in East Antarctica that can be directly correlated with an Australian equivalent in a Gondwana reconstruction. The Mesoproterozoic facies terrain comprise a series of migmatitic metapelites and metapsammites interlayered with mafic to ultramafic and felsic sequences with rare calc-silicates, large partial melt bodies (Windmill Island supacrustals), undeformed granite, charnockite, gabbro, pegmatite, aplites and cut by easterly-trending late dolerite dykes. Ardery Island and Odbert Island are part of the southern gradation of a metamorphic grade transition which separates the northern part of the Windmill Islands region from the southern part. The metamorphic grade ranges from amphibolite facies, sillimanite-biotite orthoclase in the north at Clark Peninsula, through biotite- cordierite-almandine granulite, to hornblende-orthopyroxene granulite at Browning Peninsula in the south. Ardery Island and Odbert Island together with Robinson Ridge, Holl Island, Peterson Island and the Browning Peninsula are similar geologically and are composed of Ardery charnockite. Charnockites are of granitic composition but were formed under anhydrous conditions. The Ardery Charnockite of Ardery Island and Odbert Island intrudes the Windmill metamorphics and consists of a modal assemblage of quartz + plagioclase + microcline + orthopyroxene + biotite + clinopyroxene hornblende with opaques and minor zircon and apatite. An isotopic age of about 1,200 million years for the Ardery charnockite has been established. The charnockite is prone to deep weathering and crumbles readily because of its mineral assemblage, whereas the metamorphic sequences of the northerly parts of the region have a much more stable mineral assemblage and crystalline structure. This difference has a significant influence on the distribution of vegetation in the Windmill Islands region with the northern rock types providing a more suitable substrate for slow growing lichens. Soils on the islands are poorly developed and consist of little more than rock flour, moraine and eroded material. Some soils contain small amounts of organic matter derived from excreta and feathers from the seabirds. Glaciation The Windmill Islands region was glaciated during the Late Pleistocene. The southern region of the Windmill Islands was deglaciated by 8,000 corr. yr B.P., and the northern region, including the Bailey Peninsula deglaciated by 5,500 corr. yr B.P. Isostatic uplift has occurred at a rate of 0.5 to 0.6 m/100 yr, with the upper mean marine limit, featured as ice-pushed ridges, being observed at nearby Robinson Ridge at approximately 28.5 metres. Climate The climate of the Windmill Islands region is frigid-Antarctic. Conditions at Ardery Island and Odbert Island are probably similar to those of the Casey station area approximately 12 km to the north. Meteorological data for the period 1957 to 1983 from Casey station (altitude 32 m) on the Bailey Peninsula show mean temperatures for the warmest and coldest months of 0.3 and -14.9°C, respectively, with extreme temperatures ranging from 9.2 to -41°C. Mean annual temperature for the period was –9.3°C. The climate is dry with a mean annual snowfall of 195 mm year-1 (rainfall equivalent) precipitation as rain has been recorded in summer. However, within the last 10 to 15 years the mean annual temperature has decreased to –9.1°C and the mean annual snowfall has increased to 230 mm year-1 (rainfall equivalent). On average the area experiences 96 days with gale-force winds, which are predominantly easterly in direction, off the polar ice cap.